The proposed project is an exploratory study that will describe and analyze important factors that influence the pattern of expenditures observed in the treatment of critically ill patients. We propose a two-year study at the University Hospital of the Boston University Medical Center, including physicians and patients drawn from the following four University Hospital services: 1) Medical Intensive Care Unit, 2) Cardiac Intensive Care Unit, 3) Surgical Intensive Care Unit, and 4) Oncology (cance) unit. Data sources for this study include patient medical records, patient bills (including routine charges, ancillary services, surgery, etc.), and physician questionnaires. After developing and testing the data collection instruments, there will be a one-year prospective study ot the care provided on these four units. We intent to focus on the following threes areas: (1) Provide disaggregated estimates of expenditures on the critically ill. We will separate out and describe expenditures for palliative as opposed to aggressive care, for research-related as opposed to medically mandatory care, and for routine versus ancillary services. In addition, we will provide estimates of the size of experimental, non-billed research costs. (2) Delineate and analyze the process of physician decision-making for the critically ill. (3) Analyze the contributions of social and economic factors to variations in cost of care for the critically ill.